Conventional radio frequency (RF) signal detectors, such as antennas, may be used to detect a direction from which an RF signal is received. In some conventional systems, an array of distinctly spaced RF receivers are disposed to receive an RF signal. Once received, the phase difference in the received signal between the two RF receivers is measured. With the measured phase difference and the known distance between the RF receivers, the direction from which the RF signal is received may be determined.
Many radio direction finding systems operate on a large baseline to detect low frequency RF signals having very long wavelengths. Signals of such wavelengths can travel over very long distances and are useful for direction finding for applications when the line-of-sight is limited, such as direction finding systems on ships. However, detection of signals having long wavelengths requires very large antennas with large spacing therebetween. The size and spacing of antennas currently required for direction finding limits their use.
In view of the above, it would be desirable to detect the direction of electromagnetic signals without requiring large antennas operating over a large baseline.